The Influence of Different Surface Treatments on the Mechanical Strength of Silicon Wafers

The implementation of photovoltaic solar energy based on silicon is being slowed down by the shortage of raw material. In this context, the use of thinner wafers arises as a solution reducing the amount of silicon in the photovoltaic modules. On the other hand, the manufacturing process with thinner wafers can become complicated with traditional tools. The high number of damaged wafers reduces the global yield. It’s known that edge and surface cracks and defects determine the mechanical strength of wafers. There are several ways of removing these defects e. g. subjecting wafers to a mechanical polishing or to a chemical etching. This paper shows a comparison between different surface treatments and their influence on the mechanical strength.

Isometric strength of the upper extremities in Czech men older than 18 years

The aim of this study was to compare isometric strength of the upper extremities in a sample of men from the Czech republic (n=638). Only the dominant upper limb was tested. The examined subjects were 18 years old or older. The measured values (in kilograms) were obtained via hand-held dynamometry testing (a digital hand-held dynamometer). The results of the hand-held dynamometry testing were compared across six age categories (18-29, 30-39, 40-49.... 70+ years). It was found that isometric strength of the dominant upper limb in men increases up to the age group 30-39 years and then declines. The highest average value (55.6 kg) was found in the age group 30-39 years, and expectably, the lowest values (34.4 kg) were documented in the age category 70+ years. The largest decline in isometric strength (-8.8 kg) was found between the age groups 60-69 years and 70+ years.